Earthquake sub-event scaling: new perspective for rupture determinism

Philippe J. Danré, Jiuxun Yin, Bradley P. Lipovsky, & Marine A. Denolle

Published August 7, 2018, SCEC Contribution #8296, 2018 SCEC Annual Meeting Poster #214 (PDF)

Strong ground motions during earthquake come from either a complex source time function or a complex wave propagation. We take advantage of global databases of source time functions (SCARDEC, Vallee et al. 2011, over 2,500 events and USGS, Hayes 2017, over 180 events) to explore earthquake source complexity. We use a sub-event detection method in each source time function to decompose the earthquake into sub-events that each carry a seismic moment and a duration. The strike slip earthquakes are systematically composed of more sub-events that other earthquake types. The number, the size, and the duration of sub-events grow with the earthquake magnitude. We construct a scaling of the sub-event moment Ma with the moment of the main event M0 and find that Ma ~ M0^(0.8). This allows us to estimate the earthquake magnitude using only the first few sub-events of the STF. Therefore, a magnitude estimate of earthquakes can be done with a good precision (Moment magnitude uncertainty is 0.28 at 10% of the rupture duration) before the rupture ends. We use quasi-static modeling of earthquake to explain our observations and constraint the fault strength parameter space. Our results demonstrate the importance of earthquake sub-events as the building blocks of larger ruptures.

Key Words
earthquake physics, rupture determinism, earthquake sub-event scaling

Citation
Danré, P. J., Yin, J., Lipovsky, B. P., & Denolle, M. A. (2018, 08). Earthquake sub-event scaling: new perspective for rupture determinism. Poster Presentation at 2018 SCEC Annual Meeting.

Related Projects & Working Groups
Fault and Rupture Mechanics (FARM)